I would also not recommend power tapering of the woofers. Do some searches on line array theory and driver spacing. Read Griffin's line array white paper too. Most of the information that you need will be found there.

With the upper frequency that you are working with, you might be able to space the drivers out a little more and create a taller line source without any lobing. There are many benefits to this and at your listening distance, you will take advantage of many of them. You will be loading the room (with bass) vertically. This will help a great deal with bass nulls.

Typically ESL panels are even less efficient than the Extremis (and that is before factoring in 6 of them). As long as you supply them with a baffle that supports them down to their cutoff they will be fine i'd guess. If the ESL isn't power tapered i wouldn't bother doing that with the extremis.

Originally posted by nate I think that the Extremis drivers would be really great. If you wanted you could push that 85HZ high pass down quite a ways and eliminate the need for a sub.

nate

Well, my IB sub goes to 10Hz pretty cleanly, and very , very loudly. A must to keep up with the big ESL L/R’s. Those are Martin Logan Monolith III’s.
The Sub stays, plus, it’s part of the room now

Quote:

Originally posted by nate I would also not recommend power tapering of the woofers. Do some searches on line array theory and driver spacing. Read Griffin's line array white paper too. Most of the information that you need will be found there.

With the upper frequency that you are working with, you might be able to space the drivers out a little more and create a taller line source without any lobing. There are many benefits to this and at your listening distance, you will take advantage of many of them. You will be loading the room (with bass) vertically. This will help a great deal with bass nulls.

Sounds like a great project. Which stat panel are you using?
Nate

Thanks Nate, I read the Griffin Doc and many of the LA posting on this forum for a few weeks. I wondered about just how applicable any form of tapering might be at these frequencies. I was being cautious.
While I would like to have a longer array, I’m constrained by the height of the screen and the fact that this will mount to the top of the IB Sub manifold (my sub is the first ‘Outie’ inverse manifold IB). As you can see from the pics in my IB Build story, the array would sit on top of that Sub box, which is a 22” cube. So the top of the array is at 22+48+2 = 72”.

The stat panel comes from a Martin Logan SL-3, as will the associated electronics. The housing from the original SL-3 will be ‘modified’ (i.e. the woofer cut off) to build this.

Quote:

Originally posted by planet10 Typically ESL panels are even less efficient than the Extremis (and that is before factoring in 6 of them). As long as you supply them with a baffle that supports them down to their cutoff they will be fine i'd guess. If the ESL isn't power tapered i wouldn't bother doing that with the extremis.

And i assume you are multi-amping?

dave

Yes, I’ll be using a DBX DriveRack 260 speaker processor in a 1x3 or 1 x4 config. My original concept for this involved a 1x4 crossover as follows:

However, based on what Nate said, it sounds like that’s overkill for these frequencies. I do have a 800 w (4 ohm) Sunfire amp channel dedicated to the ESL panel, and still have another 3x200 w (8 ohm) Sunfire amp channels to play with for this project. So splitting the array up is easy, but if not necessary, then I won’t.

Adire’s guidelines are for roughly 9.5L per driver in a sealed alignment, therefore the line array box is a simple tower that measures 48”x10”x12.5” to yield an internal volume of roughly 60 Liters in a sealed alignment.
Using six internal braces for reinforcement, the box is pretty simple to construct. All sides are 1” MDF. As the speaker is never really visible, the finish will be flat black paint.

Any opinions on the use of sealed vs vented for this application?
Sealed would be simpler (and smaller).

Originally posted by planet10 I'd think you'd want to maintain the dipole as far down as possible (ie extremis in an open baffle)

dave

Dave, I’m, precisely trying to avoid dipoles at these frequencies due to rear wave cancellations. The ESL panel will readily play down to 250Hz, but the cancellations are severe and cause a noticeable suck-out.

I’m looking to get clean, high SPL’s from 85 to 500Hz out of the line array. Power is not a problem (I can do 2x200w into the array), so a sealed design seemed like the best way to achieve this.

Again, as the center channel, the music and vocal ranges are often concentrated there, and I’m looking for a strong mid-bass foundation that will keep up with the ESL and the IB sub in terms of clarity and ultimate SPL.